Electrical immersion-heater.



W. W. HANSGOM & A. L. LANGERMAN. ELECTRICAL IMMBsIoN HEATER.

APPLICATION FILED MAR. 20, 1909.

Patented Sept 26, 1911.

@p'l/ Mita-rar UNITED STATES 4PM ENT OFFICE WILLIMWALIACE HANSCOM ANDALBERT LEOPOLD LANGERMAN, OF SAN FRANCISCO, CLIFORNIA.

ELECTRICAL IMMERSION-HEATER.

Specication of Letters Patent.

Patented Sept. 26, 191i.

T o all whom it may concern:

. Be it known that we, WILLIAM WALLACE. HANsooM and ALBERT L.IgANonuiuAm'citizens of the United. States, and residents ot' the cityand county of San Francisco, State of California, have invented certain,new and useful Improvements in Electrical Immersion-Heaters, of whichthe following is a specificatii..

The object'of our improvement is to provide an immersion heater, havingarrangements of parts and combinations adapted to obviatejcertaindefectscommon to immersionv heaters in present use, among which are thecomparatively long time theyr take to heat a given volume ofliquid to agiven temperature, their' subjection to loverheating when withdrawn fromthe liquid they are used to heat, and. the ditiiculty they present tothorough cleaning(f y l.

We havediscovered that Amuch of the time, -required to bring agiven,volume of liquid `tua 'given temperature Aby the agency ofelectrical immersion heaters in common use'is expended in heatingtheparts of the heater'itself, especially .where such parts comprise alarge `proportion of electrically non-Conducting material. And in the4present constructions, the arrangement lis such that the air, being avery poor conductor, retards the rapid' heating of the apparatus. By ourpeculiar method of combining' the various parts of our device and ofWinding the'wiyre, `we provide a construction that miniinlz'es theamount of insulating and supporting material employed, and mate' riallyreducesjthe retardation due to the non-conductivity of air.

The utility of providing some means of preventing electrical heatersfrom overheatlng arises not only from the danger of destruction to theapparatus itself, but to the dangerof setting lire to inflammablematerials in juxtaposition thereto. The ordinary fusing devices areuseless for this purpose, because they are operated by an increasel inthe strength of the current flowing through thacn-A Our protectingdevice operates in a different manner and does not require an increasein the current strength to cause an exercise of its function; 4

The necessity for keeping clean a heater that is intended to be immersedin a liquid required for human consumption, is obvious. Water containsimpurities whichhfxn themselves to the surfaceot an immersion heater. Byour construction'"our, beater may he thrown bodily into a vessel ofwater, and thoroughly cleaned, without endangering the inner parts byallowing moisture to reach them.

No accomplish our object hy means illustrated in the accompanyingdrawing of '\vhi`(.`:l1- i. 1 l g Figure 1 1s a vertical sectional Viewof our heater, showing fuse plug in position; Fig. 2 a plan view of ourheater with parts of casing broken away to show interior mechanism; Fig.3 the copper strip conductor, which forms an element 1n our .scheme forwinding the coil. Fig. 4 is a @detail view ofcertain connecting means. fThe drawings -are made to an enlarged .'scale in order to show the partsmore clearly. i Similar numerals of reference mark simi- {lar partsthroughout the several views.

Describing first the outer casing of our device, We provide a tube ofmetal 1 having a top 2, soldered thereon with solder having a very highfusing point. Attached to said ,top is a tube 3. which in contact withand similarly soldered to said outer casing by highfusing solder at 4.Said top is provided with an externally threaded covering 5, for ourfuse plug 6, a`nd has a screw cap 7. Said top's also provided with aninternally threaded coupling device 8, which engages .with externalthread on the metal tube 9, ,the other end of tube 9, heilig providedwith 'a hermetically sealed connectin device 10, which seals the innerpart o said -tube against the entrance of moisture.

By the described construction of the outer covering ol our heater, the'inner parts thereof containing the electrical conductors and insulatingmaterials are protected from moisture, andthe whole device fromconnector 10 to the bottom of the outer casing may be thrown into avessel of water and thoroughly cleaned. 4 Notwithstanding the watertight character of our outer envelop, the water in which our heater maybe immersed is free to flow along inher tube 3, the top .and-bottomthereof being open.

Turning now to the inner parts of our device. We provide a Vcoil bearingtube 11, of thin brass which slips over the tube 3, inside tube 1; andthe outside thereof we cover with a thin layer of mica insulation 12.Two contact and supporting brackets 13, and 14, are provided, bracket 14being shaped to tit about the mica surface 12, ol tube 11, substantiallyin the position shown. But outside' of mica strip 12, and underneathbracket 13, is a conducting strip 15, saidtrip being laid against micacovering .12 from the top to near the bottom of the tube 11, andarranged in electrical contact with bracket 13. A layer of mica 16, isplaced over the conducting si rip 15, and carried over the exposedsurface of bracket 1 3. The exposed surface of bracket 14, issimilarlyprotected from electrical contact by mens of a mica covering 1T. T ubc1l is now placed on a former and tightl Wound from top to bottom withthe desiredy number of convolutions of bare high resistance wir 18, insuch manner that a very small air space is left between theconvolutions. Part of these windings pass over brackets 13 and 14 asindicated 1n Fig. 1, and are held there firmly in position. Brackets 13and 14 serve to support the connecting devices andy fuses,

and, arranged as shown, obviate the necessit for using a large mass ofheat absorbing su'stance. The bottom end of coil 18, is soldered toconductin strip 15, by solder having a very high using point, and thetop of said coil is similarly soldered to bracket 14. The surface ofsaid coil and the inter-sticos between the convolutions are then treatedwith a cold insulating cement 18' composed of silica withl a solution ofsilicate of soda.

Brackets 13 and 14 are made as small as the requirements of space andrigidity will allow, and takenin combination with the tube 12,conducting strip A15, and the thin mica insulating covering described,form an element having a. minimum of substance to be heated. Whereforethe temperature thereof is ,more quickly raised to the desired degreethan is the case where more bulky parts are combined after the usualmanner.

Bracket 13 is rovided with a connecting screw 19, to which is attachedone of the insulated wires 20, from connector 10. Bracket 14 is providedwith a conducting plate 28 insulated therefrom whereon is attached aconnecting screw 21, to which is attached a second insulated Wire 33,from connector 10. Coil 18 is connected through said bracket 13 andthrough bracket 14, and conducting plate 2S, with connector 10. Butbracket 14, also carries our fusing apparatus in circuit with said coil,in the manner which we will now proceed to describe.

Our fuse plug consists of a brass shell 22,

rovided with a copper cap 23. A screw 24 lsfitted to the center of saidshell by means of a plug of insulating cement 25, having substantiallythe shape indicated, with,.'a convex surface below and a concavesurfaceabove, and an aperture through its center stopped by said screw. A fusewire 26,--is attached to said screw and to saidcppper Ilracket 121 isprovided with' an' insulating strip of mica i7, which supports aconducting plate 28 and is attached thereto; and plate 28 and bracket 14are bound together )y screws 29, tksaid screws passing through screwholes made so wide in plate 28 as not to touch said screws, said screwsbeing also insulated from plate 28 by insulating washers 31 and 32.

Our fuse lug is arranged with the rim of shell 22 in electrical contactwith late 28, screw 24, being electricallyl insu ated from plate 2S, andelectrically attached to bracket 14. Therefore the circuit from bracket14, to connector 10, is throu screw 24, fuse. wire 26, cap .23, shellconducting plate 28, connecting screw 21, and wire 33.

As aforesaid, our fuse plug does not operate by an increase in thestrength of the current. As the specific resistance of conducting wires.increases with their temperature, a raised temperature in coil 18 wouldtend 4to send a smaller instead of a greater cur rent through thecircuit.

So we cause our fuse to operate directly from thev heat imparted theretoby the raised temperature of the whole device. Coil 18 heats all of theelement and with it bracket 14 and screw 24, shell 22, and fuse wire 26.Said fuse Wire being made to melt at a temperature a little above thatof the whole apparatus in liquid, a 'rise in temperature to the requireddegree will melt said fuse and open the circuit.

We claim:

1. In an electrical immersion heater, heat ing conductors and',dielectrics inclosed therein, a fusing device, a prottive covering forsaid conductors and dielectrics comprising an outer tube, having abended por! tion in the lower part thereof, an inner tube having a capadapted to fit outside said outer tube and being soldered thereto byhigh fusing solder, and havin its lower portion fitted to engage saidben ed portion o said outer tube and being soldered thereto by highfusing solder, a screw capped aperture in said cap adapted to protectand'give ready access to said fusing device, an interiorly threadedportion on said cap, a tube threaded exterorly at one end to engage saidinteriorly threaded portion, and a water-tight Velectrical connectingdevice at the other end of said tube.

2. An electrical' immersion hebr oomprsing an hermetically sealedprotective coveringl having an inner tube, a coil-supporting tubesurrounding said inner tube, l.

eating coil wound on said coil-supporting tubey and insulated therefrom,supporting brackets held in position on the tube by the windings of saidcoil, connecting screws on said supporting brackets, a water-tightelectrical connector, and electrical connection between said water-lightconnector, connecting screws, brackets and said heating coil.

3. An electrical immersionheater coniprising an ermctically sealedprotective covering' having an inner tube, u coil-supporting tubesurrounding said inner tube, a heating coil wound on saidcoil-supporting tube and insulated therefrom, supporting brackets heldin position von the tube by thdgwindings of said coil, a fuse plugsupported on one of said brackets, having a fuse wire in circuit withsaid coil, a watertight connector, and electrical connections betweensaid water-tight connector and said heating coil through said fuse plug.

4. An electrical immersion heater comprising an hermetically sealedprotective covering having an innel' tube, a coil-supporting tubesurrounding said inner tube, a heat-ing coil wound on saidcoil-suporting tube and insulated therefrom, a iiracket held inpositionon the tube by the windings of said coil, a conducting strip having anupper end in electrical contact with said bracket and a lower end ofsaid heating coil, a second bracket held in position on the tube by thewindings of said coil `and electrically connected with the upper end ofsaid heating coil, and insulated from said first bracket, a water-tightconnector, and electrical connections between sa id water-tightconnector and said brackets.'

5. An electrical immersion, heater comprising an herinetically sealedcovering device having an inner tube, a coil-supporting tube surroundingsaid inner tube, 'a heating coil wound ou said coil supporting tube andinsulated therefrom, a protective fusing device including a fuse wire incircuit with said coil and arranged to be melted by excess oftemperature in the adjacent arts, a water-tight electrical connector, anlectrical connections between said heating coil and said connectorthrough said fusing device.

6. In an electrical having a heating coil, means for protection fromoverheating comprising a bracket made of material as' light asmechanically expedient, and having a threaded hole, a conducting plateresting thereon, but insulated therefrom, a fusing device comprising ashell, a cap on said shell, a illino of insulating cement, a screwembedde in said fillingr and extending beyond the lowest edge of saidshell to engage said threaded hole in lsaid bracket, an electricalconnection from said bracket to the one end of said heating coil, anelectrical connection from said conimmersi on heater,

ducting plate to an external connecting deff vice, whereby, when saidscrew is threaded in said hole, said shell is seated in electricalContact with said conducting plate.

7 In an immersion heater, a heating coil, aY protective coveringtherefor, means for electrically connecting the ends of said heatingcoil comprising a metal bracket held in position on the tube by thewindings of said coil and electrically connected with thc lower end ofsaid coil, a second metal bracket held in 4position on the tube by thewindings of said coil and electrically connected with the upper endthereof.

8. In an' ilnmersion heater, a tube, a heating coil wound on .said tube,means for establishing electrical contactwith the lower end of said coilcom rising a conducting strip insulated there om and from saidl tube andheld in position on the tube by the windings of said coil, an electricalconnection at the top of sald strip and electrical contact between thelowerend of vsaid strip` and the lower end of said coil.

In testimon whereof we have set our hands this 14t day of Januar A. D.1909, in the lpresence of the two su scribed witnesses.

` WILLMM WALLACE Hanscom.

ALBERT LEOPOLD LANGERMAN.

Witnesses:

W. A. Renners, A. H. CAINE.

